On 26/04/15 12:08, Andres Freund wrote:
On April 26, 2015 11:22:01 AM GMT+02:00, Heikki Linnakangas <hlinn...@iki.fi>
wrote:
On 04/25/2015 12:01 PM, Andres Freund wrote:
That's why I wanted the WHERE outside the (), which requires either
adding DO between the index inference clause, and the action, to
avoid
ambiguities in the grammar.
Yeah, having the WHERE outside the parens seems much nicer. What is the
ambiguity?
With a full keyword in between (like DO), there's none. But without it its
ambiguous where a trailing UPDATE belongs to. At least from the point of a LALR
grammar. WHERE UPDATE; is legal. I don't see the DO as much of a problem though.
The DO variant with WHERE outside of parenthesis sounds fine to me. Or
at least better than the alternatives I've seen or can come up with.
A couple things:
a) Why is is 'CONFLICT"? We're talking about a uniquness violation.
What
if we, at some later point, also want to handle other kind of
violations? Shouldn't it be ON UNIQUE CONFLICT/ERROR/VIOLATION
...
As Peter said, it's also for exclusion constraints. Perhaps "ON
CONSTRAINT VIOLATION"? It doesn't apply to foreign key constraints,
though. I think "ON CONFLICT" is fine.
What if we, as at least I have previously wished for, want to allow handling
other types of constraints? It'd be quite cool to be able to insert the
referenced key on a fkey violation for some use cases.
b) For me there's a WITH before the index inference clause missing,
to
have it read in 'SQL' style.
Agreed. ON would sound more natural than WITH though:
INSERT INTO mytable ON CONFLICT ON (keycol) UPDATE ...
I chose WITh because of the repeated DO; that's all ;)
The ON CONFLICT ON sounds really weird to me. Either ON CONSTRAINT
VIOLATION (foo) or ON CONFLICT [WITH] (foo) both seem acceptable.
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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